This proposal is centered on the possibility of obtaining synchronous populations of endospore-forming, gram-positive Bacilli, by selecting newborn cells from cultures growing under balanced growth conditions. Bacillus subtilis and Bacillus megaterium are the two bacteria that will be analyzed. The study will include 1) the development of methods of synchronization, 2) the analysis of the synthetic pattern of DNA, phospholipids and other macromolecules during the division cycle at a variety of growth rates, 3) the analysis of macromolecular syntheses required for cell division and for differentiation into sporangia, 4) the comparison of the cell cycles of bacteria synchronized by selection of newborn cells and by resuspension of stationary phase cultures into fresh media. The results of this study should provide key information on the process of differentiation in these cell systems. BIBLIOGRAPHIC REFERENCES: Helmstetter, C. E. and Pierucci, O. DNA Synthesis during the Division Cycle of Three Substrains of Escherichia coli B/r. J. Mol. Biol. 102, 477, 1976. Pierucci, O. and Helmstetter, C. F. Chromosome Segregation in Escherichia coli B/r at Various Growth Rates. J. Bacteriol. 128, 708, 1976.